Under the parent grant, Tetra Discovery Partners is developing phosphodiesterase 4B (PDE4B) allosteric inhibitors as a treatment for major depressive disorder. Uniquely, the Tetra drug will address inflammation as a contributor to depression. This is a new mechanism of action for an antidepressant drug which should prove complimentary to current therapeutics. The company estimates that 10-20% of patients with depression have co-morbid inflammation and will be ideal candidates for the Tetra drug. Addressing inflammation will target currently untreatable patients, such as those receiving interferon-? (IFN?) for viral illness, depressed patients with co-morbid psoriasis, inflammatory bowel disease, traumatic brain injury, or post-traumatic stress disorder. Given the limitations of current treatments, there is a need for new medications with novel mechanisms of action. The supplemental fund request will allow the company to assess the benefit of lead PDE4B allosteric inhibitors in preclinical mouse models of Alzheimer?s disease.